1. Field of Invention
This invention is directed to an interferometer that includes improved phase shifting and polarizing structures.
2. Description of Related Art
U.S. Pat. No. 6,304,330, which is incorporated herein by reference for all of its relevant teachings, discloses a novel multiple phase-shifting image generating structure that combines a wavefront-spreading element, a phase-shifting interference element and a sensing element. By combining the wavefront-spreading element, the phase-shifting interference element, and the sensing element, the multiple phase-shifting image generating structure shown in the 330 patent is able to convert many sources of potential error in interferometry measurements into common-mode errors. That is, these errors, in view of the multiple phase-shifting image generating structure disclosed in the 330 patent, equally affect all of the interferometry measurements. As a result, the magnitude and direction of these common-mode errors can be ignored when making high-precision measurements using an interferometer that includes the multiple phase-shifting image generating structure disclosed in the 330 patent.